Hybrid Poplar Care

Hybrid poplars (Populus hybrids) include Carolina poplar (P. x euramericana), tower poplar (P. x canescens "Tower") and related species, such as cottonwood (P. deltoides) and white poplar (P. alba). Care for the wide array of hybrid trees is similar across the board. Keep a close watch on these trees because they are susceptible to a variety of problems that can result in mild to severe damage. When issues arise, employ a control program as soon as possible to protect your landscape.

General Care

Consistent, appropriate care results in healthy plants with an increased capacity to fight off and recuperate from problems. Hybrid poplars thrive in areas that provide full sunlight. They prefer moist, sandy loam to clay loam soil and like a pH of 5.5 to 7.5, though they function well in most soil types and tolerate drought and pollution. Poplar hybrids perform best when grown in the U.S. Department of Agriculture (USDA) Plant Hardiness Zone to which they are suited. For example, cottonwoods (Populus deltoides) grow most successfully in USDA Zones 2 to 9.

Mulch

Mulching is beneficial for hybrid poplar trees. It is used for moisture conservation and as protection against weed growth and the insects weeds often attract to the home garden. Place a 3- to 4-inch layer of organic mulch, such as wood chips or bark, on the soil surrounding hybrid poplars without pressing it directly against the tree trunks. First, however, it is wise to take a soil sample to the county Cooperative Extension Service office for analysis. Before mulch is laid, the soil may need amendments to reach the proper acidity, nutrient content and healthy balance for hybrid poplars, and that is unlikely to be achieved without a soil test.

Sucking Pests

Hybrid poplars are susceptible to pests such as aphids and beetles. Different kinds of aphids, including gall aphids (Colopha ulmicola) and vagabond aphids (Pemphigus vagabundus), attack hybrid poplars, sucking tissue fluid from plant material while causing the development of galls, or swollen areas, on the trees. Gall-making and non-gall-making aphids have pear-shaped, soft bodies and are in a variety of colors, such as brown, green or pink. Their feeding may lead to distorted, discolored foliage and defoliation. In addition, feeding aphids secrete honeydew, a sticky, sweet substance that encourages the growth of sooty mold. Sooty mold, a black-hued fungal growth, forms wherever honeydew falls. Mold-saturated leaves cannot absorb adequate sunlight. To control aphids, release their natural enemies, such as parasitic wasps; they kill aphids without causing further harm to affected trees. Thorough applications of insecticidal soap or horticultural oils kill aphids on contact. A sooty mold problem will clear on its own once aphid populations are managed.

Chewing Pests

Leaf beetles, such as cottonwood leaf beetle (Chrysomela scripta), may attack hybrid poplar trees. In both their larval and adult stages, leaf beetles feed by chewing plant tissue, either damaging the leaf surface or eating all leaf tissue except for the veins, also known as skeletonizing. Cottonwood leaf beetles have 1/4-inch long black bodies with red to yellow markings. Leaf beetle damage may result in defoliation and, when left untreated, can lead to plant death. To care for infested trees, regularly pull and manage weeds near the hybrid poplar trees. The release of natural enemies, such as convergent lady beetles and parasitic wasps, provides biological control. In addition, applications of B.t. (Bacillus thuringiensis), a microbial insecticide, provides supplemental biological control of beetles.

Diseases

Care of hybrid poplars may include managing diseases such as leaf spots and cankers. Marssonina leaf spot causes brown spots that often display yellow borders on leaves, twig die-back and early leaf drop. Controlling the infection requires removing and destroying debris and affected plant material and applying copper-based fungicides. Septoria leaf spot, also referred to as mycosphaerella leaf spot, causes pale brown spots with dark borders on foliage, areas of dying plant tissue on twigs and subsequent die-back. Control of this disease includes applications of a fungicide with an active ingredient such as chlorothalonil. Canker diseases, such as cytospora canker, are fungal infections that attack tree branches. Bark begins to display cankers, or discolored areas of dying plant tissue, which may cause little harm or may lead to girdled branches and tree decline. Preventive and curative chemical measures are not known. For cultural prevention, maintain strict care schedules, protect trees from accidental injury and irrigate their soil during dry, warm periods.

About the Author

Tarah Damask's writing career began in 2003 and includes experience as a fashion writer/editor for Neiman Marcus, short fiction publications in "North Texas Review," a self-published novel, band biographies, charter school curriculum and articles for various websites. Damask holds a Master of Arts in English and creative writing from the University of North Texas.